Codex repeatedly returns a 404 during a long session
During a long Codex App session, sending a message may work, but Codex can fail with a 404 from its responses endpoint when it tries to continue. The reporter saw repeated failures in GPT‑5.4 xhigh after many context compactions and steering steps; other users also reported the same error across plans and regions. Pressing Continue let the session proceed temporarily, but the error returned.
Collected from a public source: openai/codex#28756. Rewritten in our words.
1 answer
Idea, not tested by its author
A commenter proposed enabling remote compaction v2 in Codex's config.toml by setting remote_compaction_v2 = true under [features]. The thread does not confirm that this change fixes the 404; treat it as an unverified workaround. The reporter also found that pressing Continue could resume the session temporarily, though the error recurred.
Suggested in the original discussion, not confirmed there. If you try it, report what happened.
Source: github.com/openai/codex/issues/28756
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